Children who are cognitively delayed are very likely to experience a range of negative educational and societal outcomes. Thus, it is important to accurately identify those factors that elevate a child's risk for cognitive delay. Yet cognitive delay's etiology is both complex and poorly understood. Few studies have used measures of the wide range of hypothesized risk factors (e.g., poverty, low birthweight, poor child health) and samples that allow for unbiased population sub-group (e.g., African Americans, Latinos, Asians) estimates. No study to date has investigated cognitive delay by repeatedly assessing the cognitive abilities of children over their first five years. This project explores the disorder's etiology using a new, nationally representative dataset, the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B). The project has two specific aims: 1) To use an unusually large, nationally representative sample of low birthweight and non-low-birthweight children, with multiple data collection points at very young ages, to examine developmental patterns of cognitive delay at 9, 24, 48, and 60 months of age, and how these are related to poverty, low birthweight, and their correlates, including single parenthood and racial/ethnic minority status;and 2) To test three types of post-birth risk factors as potential explanations for the relationships between (a) poverty, low birthweight, and their correlates, and (b) cognitive disability at 9, 24, 48, and 60 months. These additional risk factors are poor child health, inadequate parenting, and low quality childcare. The project will address these aims by fitting generalized linear mixed models to ECLS-B data for children at 9, 24, 48, and 60 months of age. In these models, child physical health, parenting quality, and caregiving will appear as time-varying covariates. By providing accurate estimates of the factors that elevate a child's risk for cognitive delay, the project will help identify promising avenues for early intervention. PUBLIC HEALTH RELEVANCE: Young children with cognitive delays are at high risk for a range of negative long-term health and social outcomes. This project will capitalize on the availability of a new, nationally representative dataset to illuminate the multiple pathways that lead to cognitive delay during young childhood, and identify promising avenues for early intervention.